Interleukin-1b Regulates the Human Brain Natriuretic Peptide Promoter via Ca-Dependent Protein Kinase Pathways

We have shown that interleukin-1b (IL-1b) activates the human brain natriuretic peptide (hBNP) promoter via a transcriptional mechanism. Others have reported that changes in intracellular calcium (Ca) mediate the action of IL-1b. We questioned whether Ca and Ca-dependent pathways mediate IL-1b regulation of the hBNP promoter in cardiac myocytes. The hBNP promoter (21818 to 1100) coupled to a luciferase cDNA reporter gene was transferred into neonatal cardiac myocytes. Cells were then treated with agents that modify Ca levels or inhibit Ca-dependent kinases, and luciferase activity was measured as an index of hBNP promoter activity. The Ca ionophore A23187 increased hBNP promoter activity; however, neither EGTA nor nifedipine reduced IL-1b–stimulated promoter activity. Long-term treatment with thapsigargin, which depletes intracellular Ca stores, decreased basal promoter activity and blocked the effect of IL-1b. Inhibition of protein kinase C completely blocked IL-1b–stimulated hBNP promoter activity, whereas inhibition of Ca/calmodulin-dependent kinase II decreased promoter activity by 40%. In contrast, inhibition of the Ca-regulated phosphatase calcineurin by cyclosporin A had no effect. These data suggest that (1) Ca activates the hBNP promoter; (2) release of Ca from intracellular stores is important to IL-1b regulation of the hBNP promoter, but transport via voltage-sensitive Ca channels is not; (3) protein kinase C and Ca/calmodulin-dependent kinase II mediate the action of IL-1b; and (4) the phosphatase calcineurin is not involved in IL-1b regulation of the hBNP promoter. Thus, Ca and Ca-dependent pathways are critical to IL-1b regulation of the hBNP promoter. (Hypertension. 2000;35[part 2]:292-296.)